The present invention relates to a rust transforming composition i.e. to a composition which can convert an oxide film on iron or steel into a corrosion-protective coating containing complexed compounds of iron in a synthetic binding agent.
The inventors have already proposed a rust transforming composition of this kind, in which the component capable of forming iron complex compounds comprises acids such as natural or synthetic aromatic oxycarboxylic acids having phenolic characteristics such as gallic acid or tannin. With this composition, a film of rust which is a mixture of iron oxides and of iron hydroxides can be converted into stable organic iron complexes which by preventing the continuous formation of new unstable iron hydroxide stop further rusting. The synthetic binding agent which is incorporated in the composition as an aqueous dispersion or emulsion forms a film which binds the organic iron complex compound and which is elastic and highly resistant to water, salt and weather.